Gasoline vapor recovery system and method

ABSTRACT

Gasoline vapor recovery system particularly adapted for bulk flow plants. The system includes an absorber into which raw gasoline vapor is introduced, as by a connection from a tank truck while the tank truck is loaded with gasoline. Light oil, such as kerosene, is pumped into the absorber and acts as a carrier, carrying the gasoline vapor through a heat exchanger and trim heater to adjust the temperature and then through a stripper, from which the gasoline is stripped from the kerosene as a vapor. The gasoline vapor is drawn from the stripper to a gas cooler by a vacuum pump and then compressed and condensed in the form of a liquid blendable into a desired grade of gasoline. The lean oil from the system may be pumped back to the absorber and reused.

United States Patent [191 Doncer et al.

[451 Jan. 21, 1975 GASOLINE VAPOR RECOVERY SYSTEM 3,714,790 2/1973 Battey 55/88 AND METHOD Primary ExaminerCharles N. Hart [75] Inventors wfi 'g x i g tti nfi Attorney, Agent, or Firm-Hill, Gross, Simpson, Van

e enox o Santen, Steadman, Chiara & Simpson [73] Assignee: Alar Engineering Corporation,

Burbank, ll]. [57] ABSTRACT [22] Filed: May 3 1973 Gasoline vapor recovery system particularly adapted for bulk flow plants. The system includes an absorber PP 357,007 into which raw gasoline vapor is introduced, as by a connection from a tank truck while the tank truck is [52] CL M 55/88 loaded with gasoline. Light oil, such as kerosene, is [51] Int Cl t t l l l l 53/14 pumped into the absorber and acts as a carrier, carry- [58] Field of 62/54, ing the gasoline vapor through a heat exchanger and 85 trim heater to adjust the temperature and then through a stripper, from which the gasoline is stripped [56] References Cited from the kerosene as a vapor. The gasoline vapor is drawn from the stripper to a gas cooler by a vacuum UNITED STATES PATENTS pump and then compressed and condensed in the Hosmer form of a blendable into a desired grade of gas- $33222" oline. The lean oil from the system may be pumped 3:242:646 3/1966 Miller et al. 55/68 back to h absorber and reused 3,463,603 8/1969 Freitas et a1. 55/68 Claims, 2 Drawing Figures .18 {"""""L tfi au 49 LACCUMULATOR l OIL TRIM J COOLER o ABSORBER /1O 0 43 A7 41 TRIM HEATER 25 HEAT EXCHANGER 42 no; 7 16 2 32 47 RICH OIL LEAN OlL STORAGE STORAGE PATENTED JAN? 1 3,861 $90 SHEET 20F 2 ,Fi'g: 2

GAS COOLER 52 STRPPER A I DRIPTANK VACUUM 46 45 PUMP AIR COOLED v 15 CONDENSER DRIP TANK SURGE TANK COMPRESSOR 62 GASOLINE VAPOR RECOVERY SYSTEM AND METHOD BACKGROUND OF THE INVENTION 1. Field of the Invention Recovery system for gasoline vapor by the use of a lean oil as a carrier.

2. The Prior Art Heretofore air gasoline vapors, generated by bulk loading operations have been recovered by refrigeration. Such methods of recovering gasoline vapors are expensive and complicated and usually require a high degree of maintenance and, therefore, are uneconomical for the average bulk gasoline terminal operation.

The present invention provides a simple and economical system for recovering gasoline vapors generated by bulk loading operations by the use of a light oil as a carrier, which may be kerosene, and then stripping the light oil from the vapor by vacuum, and recovering the gasoline by compressing and condensing the stripped vapor.

An advantage of the present invention is in the simplification in the recovery of gasoline vapors or other hydrocarbons by using a light oil as a carrier for the hydrocarbons and stripping the oil from the hydrocarbon vapor enabling the hydrocarbon vapor to be compressed and condensed for reblending for storage and reuse.

Another advantage of the present invention is in the simplification of the recovery of gasoline vapors without the need for the complicated and expensive refrigeration systems heretofore necessary for such purposes.

Still another advantage of the invention is the provision of a recovery system for gasoline vapors utilizing kerosene as a carrier, which may be recovered for reuse and recycled as stripped from the gasoline vapor.

A further advantage of the invention is in the efficiency and low operating cost of the gas vapor recovering system, making it particularly adapted for bulk terminal operations.

Other objects, features and advantages of the invention will be readily apparent from the following description of certain preferred embodiments thereof, taken in conjunction with the accompanying drawings, although variations and modifications may be effected without departing from the spirit and scope of the novel concepts of the disclosure.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic view diagrammatically illustrating one-half of the recovery system; and

FIG. 2 is a diagrammatic view forming in effect a continuation of FIG. 1 and illustrating the balance of the system.

DESCRIPTION OF PREFERRED EMBODIMENTS OF INVENTION In the embodiment of the invention illustrated in the drawings, the system of recovering the gasoline from the gasoline vapors consists essentially of an absorbing column 10, a stripping column 11, a vacuum pump 12, a compressor 13 and a condenser 15, all connected in series.

The absorber 10 may be of any conventional form 6 and has an inlet line 16 for gasoline vapor shown as being disposed beneath packing 17 of the absorber. A

Component Summer Winter C 1% 1% iC l l% l5% nC. 9% l2% C 10% l0% C 2% 2% C, 2% 2% Air 58% where C is propane; iC is isobutane; nC, is N butane; C is pentane; C is hexane; and C is heptane.

An inlet 19 for light oil, such as kerosene, enters the top of the adsorber and passes downwardly through the packing therein and mixes with the gas vapor and acts as a carrier therefor. An outlet 20 may lead from the top of the absorber to a pump 21, for essentially removing air from the absorber and discharging the air to atmosphere,

As shown in FIG. 1, a lean oil storage tank 22 is provided for storing a lean oil such as kerosene, to be delivered to the lean oil inlet 19 through a pump 23 connected with a pipeline 24 leading from said pump to the inlet line 19. A flow control 25 is provided in the inlet line 16 for gas vapor. Said flow control may be a flow sensor and may have control connection with a control valve 26 in the inlet line 24 for lead oil, to admit lean oil intothe absorber at a rate proportionate to the admission of gasoline vapor into the absorber.

While we have herein shown a lean oil storage tank in the system, it should be understood that if desired the lean oil storage tank and pump may be dispensed with and that an accumulator 18 may be instead used to supply the lean oil to the adsorber. The accumulator 18 is diagrammatically shown by broken lines in FIG. 1 to indicate it may be an alternative form of the invention, and may be of any suitable conventional form so need not herein be shown or described in detail.

The air gas mixture mixed with the light oil in the absorber will result in a rich oil at the bottom of the ab sorber, which may be pumped from the absorber by a pump 27 under the control of a valve 29. From the pump 27 the rich oil may be pumped to a heat exchanger 30 through a line 31, at which point the components, for example, may be as follows:

Mol.%

C 016 iC 2.06 nC. l.7l G 205 C 0.65 C, 1.04 Sol. 92.32

inch at the rate of 254 cubic feet per minute in an exemplary system of the capacity described.

A return line 32 for the rich oil is shown as leading to the top of a rich oil storage tank 33. The storage tank for rich oil need only be provided where the system does not use an accumulator. A valve 36 controls the return of rich oil to the rich oil storage tank, while a pump 37 is provided to pump rich oil from the rich oil storage tank to the inlet line 31 to the heat exchanger 30.

A trim cooler 40 is connected with the heat exchanger 30 adjacent the inlet end thereof through a line 41. The trim cooler 40 serves as an additional heat exchanger to adjust the temperature and may pump the gas vapor and the solvent mixture to the absorber through the inlet line 19 to the top of the absorber. The components of this mixture, for example, may be as follows:

The trim cooler 40 may be a conventional form of cooler well-known to those skilled in the art, so need only be shown diagrammatically herein, and, for example, may have a capacity of 53,000 B.T.U. per hour at an operating temperature of 112F.

The gasoline vapor mixed with oil passes from the heat exchanger to a trim heater 42, which may be in the form of a second heat exchanger which for a basic unit of 50 cfm may have an operating capacity of 100,000 B.T.U. per hour and an operating temperature of 208F. with a design capacity of 112,000 B.T.U. per hour and a design temperature of 600F. and a design pressure of 125 psi.

The solution of gasoline and kerosene is passed through the trim heater 42 under the control of a system of valves 43 through a line 44 to the top portion of the stripper column 11, where the kerosene or light oil is separated from the gasoline vapor. A valve 45 and pump 46 may return the kerosene or light oil to the heat exchanger, adjacent the outlet end thereof, under the control of the valve 45 and a system of valves 47, to thereby recirculate the light oil.

A gas cooler 48 is connected with the top of the stripper 11 through a line 49 to withdraw the gasoline vapor removed from the light carrier oil and cool the vapor and allow the cooled vapor to drop into a drip tank 50. The gas cooler 48 may be similar in construction to the trim cooler 40 with an air rate capacity in the order of 6,500 B.T.U. per hour.

The vacuum pump 12 is connected with the drip tank through a line 52 under control of a valve 53 and withdraws the gasoline vapor and passes the vapor to a second gas cooler 54 having a second drip tank 55 disposed therebeneath and connected therewith through a line 56.

The compressor 13 is connected to the second drip tank 55 through a line 56 having a valve 57 therein. Said compressor compresses the gasoline vapor conducted from the vacuum pump 12 to the air cooled Comp. MoLFr.

C Nil iC 0.3163 nC. 0.2580 C 0.3006 C 0.0623 C, 0.0620

Vapors from the condenser 15 may be recycled to the absorbing column through a line 65 leading from the condenser 15 and connected with a line 66 having fluid connection with the intake line 16. A system of control and bypass valves 67 is connected in a recycling line 66 to control the recycling of the vapors not condensed. The line 66 is also connected to the top of the surge tank 60, to recycle vapors in said tank.

Where an accumulator such as the accumulator 18 is provided in the system, the same components are in the system except the lean oil storage tank 22 and the rich oil storage tank 33 need not be used. The light oil is thus applied from a suitable source of supply through the accumulator 18 to the lean oil inlet line 19, connected from the trim cooler 40 to the top part of the absorber 10, which line also transmits oil and gasoline vapor from the heat exchanger 30 and trim cooler 40 to be absorbed by the lean oil.

In this system, the flow controller 25 and pumps 23 and 37 may be dispensed with, and the gasoline vapor may be compressed in the compressor to pressures in the order of 200 psi and condensed as a liquid suitable for blending into regular grade gasoline, as previously described. Vapors from the condenser may also be recycled to the absorbing column to insure the maximum possible recovery, as previously described.

Certain of the valves and controls for the pumps and other components may be electrically operated and controlled to enable suitable control means (not shown) of a form known to those skilled in the art to make the system fully automatic. With a basic unit having an accumulator, without the rich oil and lean oil storage tanks, at the start of the day, the operator may start the system by depressing a start button (not shown). The vacuum pump 12, oil circulating pump 27 and heat exchangers 30 and 42 start and the system remains in a warm-up condition until normal operating conditions are established. The trim coolers 40,48,54, compressor 13 and condenser 15 will also start. As normal operating conditions are established, a ready" light (not shown) on a control panel (not shown) may flash and the operator may open a valve 70 which may be a safety valve of a well-known form, to admit the airgasoline mixture to the adsorber. No further operator attention is required, as the system is self-adjusting over the entire range of operating conditions. At the end of the operating day, the operator may depress a stop" button (not shown). The safety valve 70 will then close and the system will purge any gas vapors remaining by the pump 21, prior to actual shut down.

Other controls of a conventional form and no part of the present invention may also be provided to cause the system to shut down and purge upon a malfunction of the system, which may be indicated on an annunciator panel (not shown) and the sounding of an alarm (not shown).

Where an accumulator is not in the system, the lean oil storage tank 22 and rich oil storage tank 33 take the place of the accumulator. The operation of the system is, however, similar to the operation of the system using the accumulator, except the scrubbing system controls and the recovery system controls are separate. The scrubbing system may be started by depressing a scrubber start" button (not shown). The lean oil pump 23, trim cooler 40 and control system therefor may start and the loading operations may begin. When sufficient rich oil has accumulated in the storage tank 33, the operator may start the recovery system by depressing a recovery start button (not shown). This will circulate the oil back to the rich oil tank until normal operating conditions are established. The valve 45, which may be a solenoid operated valve, may then transfer the oil from the bottom of the stripper 11 to the heat exchanger under the control of the pump 46. The series of valves 47 may also include a bypass line 470 having a valve 47b therein which may be solenoid operated, to enable the lean oil leaving the heat exchanger to be pumped to the lean oil storage tank through a line 22a, for recirculation over the adsorber. It is, of course, understood that when lean oil is returned to the lean oil storage tank, the valves 47 are closed. The cooler 40, vacuum pump 12, cooler 48, compressor 13 and condenser 15 are then in operation to deliver the recovered gas from the surge tank 60 and recycle any remaining gasoline vapors back to the inlet line 16.

It should be understood that the system just described in exemplary only and may be of various sizes and capacities, with the resultant varying volumes and pressures from those mentioned herein.

It should also be understood that the system is adaptable for various hydrocarbons with different components from those mentioned in the examples and the percentages of components of the vapor may vary under different outside temperature conditions.

We claim as our invention:

1. In a method of recovering gasoline from gasoline vapor, including the provision of a lean oil storage tank and a rich oil storage tank,

establishing a constant feed of lean oil from the lean oil storage tank to an absorber.

withdrawing rich oil from the bottom of the absorber and passing to the rich oil storage tank.

passing the rich oil from the rich oil storage tank through a heat exchanger,

passing part of the oil from the heat exchanger to a trim cooler,

forcing the oil by the trim cooler to the absorber, and

passing the oil from the first heat exchanger through a second heat exchanger to a stripper and stripping the gasoline vapor from the the rich oil, removing the gasoline as a vapor by vacuum,

and then compressing and condensing the vapor and withdrawing the condensed vapor by blending in the form of a required gasoline mixture.

2. The method of claim 1, including the sensing of the flow of gasoline vapor to the absorber, and

controlling the flow of lean oil to the absorber and thereby balancing the flow of lean oil to the absorber in accordance with flow of gasoline vapor thereto.

3. The method of claim 1, wherein the vapor remaining after the condensing operation is recycled through the absorber.

4. The method of claim 1, wherein the heavy oil is passed through a plurality of heat exchangers in series with the stripper and the oil stripped from the gasoline in the stripper is recirculated through the heat exchanger.

5. The method of claim 1, wherein the gasoline vapor is supplied to the absorber through an accumulator at atmospheric pressure and at a temperature in the order of 

1. IN A METHOD OF RECOVERING GASOLINE FROM GASOLINE VAPOR, INCLUDING THE PROVISION OF A LEAN OIL STORAGE TANK AND A RICH OIL STORAGE TANK, ESTABLISHING A CONSTANT FEED OF LEAN OIL FROM THE LEAN OIL STORAGE TANK TO AN ABSORBER, WITHDRAWING RICH OIL FROM THE BOTTOM OF THE ABSORBER AND PASSING TO THE RICH OIL STORAGE TANK, PASSING THE RICH OIL FROM THE RICH OIL STORAGE TANK THROUGH A HEAT EXCHANGER, PASSING PART OF THE OIL FROM THE HEAT EXCHANGER TO A TRIM COOLER, FORCING THE OIL BY THE TRIM COOLER TO THE ABSORBER, AND PASSING THE OIL FROM THE FIRST HEAT EXCHANGER THROUGH A SECOND HEAT EXCHANGER TO S STRIPPER AND STRIPPING THE GASOLINE VAPOR FROM THE RICH OIL, REMOVING THE GASOLINE AS A VAPOR BY VACUUM, AND THEN COMPRESSING AND CONDENSING THE VAPOR AND WITHDRAWING THE CONDENSED VAPOR BY BLENDING IN THE FORM OF A REQUIRED GASOLINE MIXTURE.
 2. The method of claim 1, including the sensing of the flow of gasoline vapor to the absorber, and controlling the flow of lean oil to the absorber and thereby balancing the flow of lean oil to the absorber in accordance with flow of gasoline vapor thereto.
 3. The method of claim 1, wherein the vapor remaining after the condensing operation is recycled through the absorber.
 4. The method of claim 1, wherein the heavy oil is passed through a plurality of heat exchangers in series with the stripper and the oil stripped from the gasoline in the stripper is recirculated through the heat exchanger.
 5. The method of claim 1, wherein the gasoline vapor is supplied to the absorber through an accumulator at atmospheric pressure and at a temperature in the order of 90*. 